/*
4coder_code_index.cpp - Generic code indexing system for layout, definition jumps, etc.
*/

// TOP

global Code_Index global_code_index = {};

////////////////////////////////
// NOTE(allen): Lookups

// TODO(allen): accelerator for these nest lookups?
// Looks like the only one I ever actually use is the file one, not the array one.
function Code_Index_Nest*
code_index_get_nest_(Code_Index_Nest_Ptr_Array *array, i64 pos){
Code_Index_Nest *result = 0;
i32 count = array->count;
Code_Index_Nest **nest_ptrs = array->ptrs;
for (i32 i = 0; i < count; i += 1){
Code_Index_Nest *nest = nest_ptrs[i];
if (nest->open.max <= pos && pos <= nest->close.min){
Code_Index_Nest *sub_nest = code_index_get_nest_(&nest->nest_array, pos);
if (sub_nest != 0){
result = sub_nest;
}
else{
result = nest;
}
break;
}
}
return(result);
}

function Code_Index_Nest*
code_index_get_nest(Code_Index_File *file, i64 pos){
return(code_index_get_nest_(&file->nest_array, pos));
}

function Code_Index_Note_List*
code_index__list_from_string(String_Const_u8 string){
u64 hash = table_hash_u8(string.str, string.size);
Code_Index_Note_List *result = &global_code_index.name_hash[hash % ArrayCount(global_code_index.name_hash)];
return(result);
}

function Code_Index_Note*
code_index_note_from_string(String_Const_u8 string){
Code_Index_Note_List *list = code_index__list_from_string(string);
Code_Index_Note *result = 0;
for (Code_Index_Note *node = list->first;
     node != 0;
     node = node->next_in_hash){
if (string_match(string, node->text)){
result = node;
break;
}
}
return(result);
}


////////////////////////////////
// NOTE(allen): Global Code Index

function void
code_index_init(void){
global_code_index.mutex = system_mutex_make();
global_code_index.node_arena = make_arena_system(KB(4));
global_code_index.buffer_to_index_file = make_table_u64_u64(global_code_index.node_arena.base_allocator, 500);
}

function Code_Index_File_Storage*
code_index__alloc_storage(void){
Code_Index_File_Storage *result = global_code_index.free_storage;
if (result == 0){
result = push_array_zero(&global_code_index.node_arena, Code_Index_File_Storage, 1);
}
else{
sll_stack_pop(global_code_index.free_storage);
}
zdll_push_back(global_code_index.storage_first, global_code_index.storage_last, result);
global_code_index.storage_count += 1;
return(result);
}

function void
code_index__free_storage(Code_Index_File_Storage *storage){
zdll_remove(global_code_index.storage_first, global_code_index.storage_last, storage);
global_code_index.storage_count -= 1;
sll_stack_push(global_code_index.free_storage, storage);
}

function void
code_index_push_nest(Code_Index_Nest_List *list, Code_Index_Nest *nest){
sll_queue_push(list->first, list->last, nest);
list->count += 1;
}

function Code_Index_Nest_Ptr_Array
code_index_nest_ptr_array_from_list(Arena *arena, Code_Index_Nest_List *list){
Code_Index_Nest_Ptr_Array array = {};
array.ptrs = push_array_zero(arena, Code_Index_Nest*, list->count);
array.count = list->count;
i32 counter = 0;
for (Code_Index_Nest *node = list->first;
     node != 0;
     node = node->next){
array.ptrs[counter] = node;
counter += 1;
}
return(array);
}

function Code_Index_Note_Ptr_Array
code_index_note_ptr_array_from_list(Arena *arena, Code_Index_Note_List *list){
Code_Index_Note_Ptr_Array array = {};
array.ptrs = push_array_zero(arena, Code_Index_Note*, list->count);
array.count = list->count;
i32 counter = 0;
for (Code_Index_Note *node = list->first;
     node != 0;
     node = node->next){
array.ptrs[counter] = node;
counter += 1;
}
return(array);
}

function void
code_index_lock(void){
system_mutex_acquire(global_code_index.mutex);
}

function void
code_index_unlock(void){
system_mutex_release(global_code_index.mutex);
}

function void
code_index__hash_file(Code_Index_File *file){
for (Code_Index_Note *node = file->note_list.first;
     node != 0;
     node = node->next){
Code_Index_Note_List *list = code_index__list_from_string(node->text);
zdll_push_back_NP_(list->first, list->last, node, next_in_hash, prev_in_hash);
list->count += 1;
}
}

function void
code_index__clear_file(Code_Index_File *file){
for (Code_Index_Note *node = file->note_list.first;
     node != 0;
     node = node->next){
Code_Index_Note_List *list = code_index__list_from_string(node->text);
zdll_remove_NP_(list->first, list->last, node, next_in_hash, prev_in_hash);
list->count -= 1;
}
}

function void
code_index_set_file(Buffer_ID buffer, Arena arena, Code_Index_File *index){
Code_Index_File_Storage *storage = 0;
Table_Lookup lookup = table_lookup(&global_code_index.buffer_to_index_file, buffer);
if (lookup.found_match){
u64 val = 0;
table_read(&global_code_index.buffer_to_index_file, lookup, &val);
storage = (Code_Index_File_Storage*)IntAsPtr(val);
code_index__clear_file(storage->file);
linalloc_clear(&storage->arena);
}
else{
storage = code_index__alloc_storage();
table_insert(&global_code_index.buffer_to_index_file, buffer, (u64)PtrAsInt(storage));
}
storage->arena = arena;
storage->file = index;

code_index__hash_file(index);
}

function void
code_index_erase_file(Buffer_ID buffer){
Table_Lookup lookup = table_lookup(&global_code_index.buffer_to_index_file, buffer);
if (lookup.found_match){
u64 val = 0;
table_read(&global_code_index.buffer_to_index_file, lookup, &val);
Code_Index_File_Storage *storage = (Code_Index_File_Storage*)IntAsPtr(val);

code_index__clear_file(storage->file);

linalloc_clear(&storage->arena);
table_erase(&global_code_index.buffer_to_index_file, lookup);
code_index__free_storage(storage);
}
}

function Code_Index_File*
code_index_get_file(Buffer_ID buffer){
Code_Index_File *result = 0;
Table_Lookup lookup = table_lookup(&global_code_index.buffer_to_index_file, buffer);
if (lookup.found_match){
u64 val = 0;
table_read(&global_code_index.buffer_to_index_file, lookup, &val);
Code_Index_File_Storage *storage = (Code_Index_File_Storage*)IntAsPtr(val);
result = storage->file;
}
return(result);
}

function void
index_shift(i64 *ptr, Range_i64 old_range, u64 new_size){
i64 i = *ptr;
if (old_range.min <= i && i < old_range.max){
*ptr = old_range.first;
}
else if (old_range.max <= i){
*ptr = i + new_size - (old_range.max - old_range.min);
}
}

function void
code_index_shift(Code_Index_Nest_Ptr_Array *array,
                 Range_i64 old_range, u64 new_size){
i32 count = array->count;
Code_Index_Nest **nest_ptr = array->ptrs;
for (i32 i = 0; i < count; i += 1, nest_ptr += 1){
Code_Index_Nest *nest = *nest_ptr;
index_shift(&nest->open.min, old_range, new_size);
index_shift(&nest->open.max, old_range, new_size);
if (nest->is_closed){
index_shift(&nest->close.min, old_range, new_size);
index_shift(&nest->close.max, old_range, new_size);
}
code_index_shift(&nest->nest_array, old_range, new_size);
}
}

function void
code_index_shift(Code_Index_File *file, Range_i64 old_range, u64 new_size){
code_index_shift(&file->nest_array, old_range, new_size);
}


////////////////////////////////
// NOTE(allen): Parser Helpers

function void
generic_parse_inc(Generic_Parse_State *state){
if (!token_it_inc_all(&state->it)){
state->finished = true;
}
}

function void
generic_parse_skip_soft_tokens(Code_Index_File *index, Generic_Parse_State *state){
Token *token = token_it_read(&state->it);
for (;token != 0 && !state->finished;){
if (state->in_preprocessor && !HasFlag(token->flags, TokenBaseFlag_PreprocessorBody)){
break;
}
if (token->kind == TokenBaseKind_Comment){
state->handle_comment(state->app, state->arena, index, token, state->contents);
}
else if (token->kind == TokenBaseKind_Whitespace){
Range_i64 range = Ii64(token);
u8 *ptr = state->contents.str + range.one_past_last - 1;
for (i64 i = range.one_past_last - 1;
     i >= range.first;
     i -= 1, ptr -= 1){
if (*ptr == '\n'){
state->prev_line_start = ptr + 1;
break;
}
}
}
else{
break;
}
generic_parse_inc(state);
token = token_it_read(&state->it);
}
}

function void
generic_parse_init(Application_Links *app, Arena *arena, String_Const_u8 contents, Token_Array *tokens, Generic_Parse_Comment_Function *handle_comment, Generic_Parse_State *state){
state->app = app;
state->arena = arena;
state->contents = contents;
state->it = token_iterator(0, tokens);
state->handle_comment = handle_comment;
state->prev_line_start = contents.str;
}

////////////////////////////////
// NOTE(allen): Parser

#if 0
/*
// NOTE(allen): grammar syntax
(X) = X
X Y = X and then Y
X? = zero or one X
$X = check for X but don't consume
[X] = zero or more Xs
X | Y = either X or Y
* = anything that does not match previous options in a X | Y | ... chain
* - X = anything that does not match X or previous options in a Y | Z | ... chain
<X> = a token of type X
"X" = literally the string "X"
X{Y} = X with flag Y

// NOTE(allen): grammar of code index parse
file: [preprocessor | scope | parens | function | type | * - <end-of-file>] <end-of-file>
preprocessor: <preprocessor> [scope | parens | stmnt]{pp-body}
scope: <scope-open> [preprocessor | scope | parens | * - <scope-close>] <scope-close>
paren: <paren-open> [preprocessor | scope | parens | * - <paren-close>] <paren-close>
stmnt-close-pattern: <scope-open> | <scope-close> | <paren-open> | <paren-close> | <stmnt-close> | <preprocessor>
stmnt: [type | * - stmnt-close-pattern] stmnt-close-pattern
type: struct | union | enum | typedef
struct: "struct" <identifier> $(";" | "{")
union: "union" <identifier> $(";" | "{")
enum: "enum" <identifier> $(";" | "{")
typedef: "typedef" [* - (<identifier> (";" | "("))] <identifier> $(";" | "(")
function: <identifier> >"(" ["(" ")" | * - ("(" | ")")] ")" ("{" | ";")
*/
#endif

function Code_Index_Note*
index_new_note(Code_Index_File *index, Generic_Parse_State *state, Range_i64 range, Code_Index_Note_Kind kind, Code_Index_Nest *parent){
Code_Index_Note *result = push_array(state->arena, Code_Index_Note, 1);
sll_queue_push(index->note_list.first, index->note_list.last, result);
index->note_list.count += 1;
result->note_kind = kind;
result->pos = range;
result->text = push_string_copy(state->arena, string_substring(state->contents, range));
result->file = index;
result->parent = parent;
return(result);
}

function void
cpp_parse_type_structure(Code_Index_File *index, Generic_Parse_State *state, Code_Index_Nest *parent){
generic_parse_inc(state);
generic_parse_skip_soft_tokens(index, state);
if (state->finished){
return;
}
Token *token = token_it_read(&state->it);
if (token != 0 && token->kind == TokenBaseKind_Identifier){
generic_parse_inc(state);
generic_parse_skip_soft_tokens(index, state);
Token *peek = token_it_read(&state->it);
if (peek != 0 && peek->kind == TokenBaseKind_StatementClose ||
    peek->kind == TokenBaseKind_ScopeOpen){
index_new_note(index, state, Ii64(token), CodeIndexNote_Type, parent);
}
}
}

function void
cpp_parse_type_def(Code_Index_File *index, Generic_Parse_State *state, Code_Index_Nest *parent){
generic_parse_inc(state);
generic_parse_skip_soft_tokens(index, state);
for (;;){
b32 did_advance = false;
Token *token = token_it_read(&state->it);
if (token == 0 || state->finished){
break;
}
if (token->kind == TokenBaseKind_Identifier){
generic_parse_inc(state);
generic_parse_skip_soft_tokens(index, state);
did_advance = true;
Token *peek = token_it_read(&state->it);
if (peek != 0 && peek->kind == TokenBaseKind_StatementClose ||
    peek->kind == TokenBaseKind_ParentheticalOpen){
index_new_note(index, state, Ii64(token), CodeIndexNote_Type, parent);
break;
}
}
else if (token->kind == TokenBaseKind_StatementClose ||
         token->kind == TokenBaseKind_ScopeOpen ||
         token->kind == TokenBaseKind_ScopeClose ||
         token->kind == TokenBaseKind_ScopeOpen ||
         token->kind == TokenBaseKind_ScopeClose){
break;
}
else if (token->kind == TokenBaseKind_Keyword){
String_Const_u8 lexeme = string_substring(state->contents, Ii64(token));
if (string_match(lexeme, string_u8_litexpr("struct")) ||
    string_match(lexeme, string_u8_litexpr("union")) ||
    string_match(lexeme, string_u8_litexpr("enum"))){
break;
}
}
if (!did_advance){
generic_parse_inc(state);
generic_parse_skip_soft_tokens(index, state);
}
}
}

function void
cpp_parse_function(Code_Index_File *index, Generic_Parse_State *state, Code_Index_Nest *parent){
Token *token = token_it_read(&state->it);
generic_parse_inc(state);
generic_parse_skip_soft_tokens(index, state);
if (state->finished){
return;
}
Token *peek = token_it_read(&state->it);
Token *reset_point = peek;
if (peek != 0 && peek->sub_kind == TokenCppKind_ParenOp){
b32 at_paren_close = false;
i32 paren_nest_level = 0;
for (; peek != 0;){
generic_parse_inc(state);
generic_parse_skip_soft_tokens(index, state);
peek = token_it_read(&state->it);
if (peek == 0 || state->finished){
break;
}

if (peek->kind == TokenBaseKind_ParentheticalOpen){
paren_nest_level += 1;
}
else if (peek->kind == TokenBaseKind_ParentheticalClose){
if (paren_nest_level > 0){
paren_nest_level -= 1;
}
else{
at_paren_close = true;
break;
}
}
}

if (at_paren_close){
generic_parse_inc(state);
generic_parse_skip_soft_tokens(index, state);
peek = token_it_read(&state->it);
if (peek != 0 &&
    peek->kind == TokenBaseKind_ScopeOpen ||
    peek->kind == TokenBaseKind_StatementClose){
index_new_note(index, state, Ii64(token), CodeIndexNote_Function, parent);
}
}
}
state->it = token_iterator(state->it.user_id, state->it.tokens, state->it.count, reset_point);
}

function Code_Index_Nest*
generic_parse_statement(Code_Index_File *index, Generic_Parse_State *state);

function Code_Index_Nest*
generic_parse_preprocessor(Code_Index_File *index, Generic_Parse_State *state);

function Code_Index_Nest*
generic_parse_scope(Code_Index_File *index, Generic_Parse_State *state);

function Code_Index_Nest*
generic_parse_paren(Code_Index_File *index, Generic_Parse_State *state);

function Code_Index_Nest*
generic_parse_statement(Code_Index_File *index, Generic_Parse_State *state){
Token *token = token_it_read(&state->it);
Code_Index_Nest *result = push_array_zero(state->arena, Code_Index_Nest, 1);
result->kind = CodeIndexNest_Statement;
result->open = Ii64(token->pos);
result->close = Ii64(max_i64);
result->file = index;

state->in_statement = true;

for (;;){
generic_parse_skip_soft_tokens(index, state);
token = token_it_read(&state->it);
if (token == 0 || state->finished){
break;
}

if (state->in_preprocessor){
if (!HasFlag(token->flags, TokenBaseFlag_PreprocessorBody) ||
    token->kind == TokenBaseKind_Preprocessor){
result->is_closed = true;
result->close = Ii64(token->pos);
break;
}
}
else{
if (token->kind == TokenBaseKind_Preprocessor){
result->is_closed = true;
result->close = Ii64(token->pos);
break;
}
}

if (token->kind == TokenBaseKind_ScopeOpen ||
    token->kind == TokenBaseKind_ScopeClose ||
    token->kind == TokenBaseKind_ParentheticalOpen){
result->is_closed = true;
result->close = Ii64(token->pos);
break;
}

if (token->kind == TokenBaseKind_StatementClose){
result->is_closed = true;
result->close = Ii64(token);
generic_parse_inc(state);
break;
}

generic_parse_inc(state);
}

state->in_statement = false;

return(result);
}

function Code_Index_Nest*
generic_parse_preprocessor(Code_Index_File *index, Generic_Parse_State *state){
Token *token = token_it_read(&state->it);
Code_Index_Nest *result = push_array_zero(state->arena, Code_Index_Nest, 1);
result->kind = CodeIndexNest_Preprocessor;
result->open = Ii64(token->pos);
result->close = Ii64(max_i64);
result->file = index;

state->in_preprocessor = true;

b32 potential_macro  = false;
if (state->do_cpp_parse){
if (token->sub_kind == TokenCppKind_PPDefine){
potential_macro = true;
}
}

generic_parse_inc(state);
for (;;){
generic_parse_skip_soft_tokens(index, state);
token = token_it_read(&state->it);
if (token == 0 || state->finished){
break;
}

if (!HasFlag(token->flags, TokenBaseFlag_PreprocessorBody) ||
    token->kind == TokenBaseKind_Preprocessor){
result->is_closed = true;
result->close = Ii64(token->pos);
break;
}

if (state->do_cpp_parse && potential_macro){
if (token->sub_kind == TokenCppKind_Identifier){
index_new_note(index, state, Ii64(token), CodeIndexNote_Macro, result);
}
potential_macro = false;
}

if (token->kind == TokenBaseKind_ScopeOpen){
Code_Index_Nest *nest = generic_parse_scope(index, state);
nest->parent = result;
code_index_push_nest(&result->nest_list, nest);
continue;
}

if (token->kind == TokenBaseKind_ParentheticalOpen){
Code_Index_Nest *nest = generic_parse_paren(index, state);
nest->parent = result;
code_index_push_nest(&result->nest_list, nest);
continue;
}

generic_parse_inc(state);
}

result->nest_array = code_index_nest_ptr_array_from_list(state->arena, &result->nest_list);

state->in_preprocessor = false;

return(result);
}

function Code_Index_Nest*
generic_parse_scope(Code_Index_File *index, Generic_Parse_State *state){
Token *token = token_it_read(&state->it);
Code_Index_Nest *result = push_array_zero(state->arena, Code_Index_Nest, 1);
result->kind = CodeIndexNest_Scope;
result->open = Ii64(token);
result->close = Ii64(max_i64);
result->file = index;

state->scope_counter += 1;

generic_parse_inc(state);
for (;;){
generic_parse_skip_soft_tokens(index, state);
token = token_it_read(&state->it);
if (token == 0 || state->finished){
break;
}

if (state->in_preprocessor){
if (!HasFlag(token->flags, TokenBaseFlag_PreprocessorBody) ||
    token->kind == TokenBaseKind_Preprocessor){
break;
}
}
else{
if (token->kind == TokenBaseKind_Preprocessor){
Code_Index_Nest *nest = generic_parse_preprocessor(index, state);
code_index_push_nest(&index->nest_list, nest);
continue;
}
}

if (token->kind == TokenBaseKind_ScopeClose){
result->is_closed = true;
result->close = Ii64(token);
generic_parse_inc(state);
break;
}

if (token->kind == TokenBaseKind_ScopeOpen){
Code_Index_Nest *nest = generic_parse_scope(index, state);
nest->parent = result;
code_index_push_nest(&result->nest_list, nest);
continue;
}

if (token->kind == TokenBaseKind_ParentheticalClose){
generic_parse_inc(state);
continue;
}

if (token->kind == TokenBaseKind_ParentheticalOpen){
Code_Index_Nest *nest = generic_parse_paren(index, state);
nest->parent = result;
code_index_push_nest(&result->nest_list, nest);

// NOTE(allen): after a parenthetical group we consider ourselves immediately
// transitioning into a statement
nest = generic_parse_statement(index, state);
nest->parent = result;
code_index_push_nest(&result->nest_list, nest);

continue;
}

{
Code_Index_Nest *nest = generic_parse_statement(index, state);
nest->parent = result;
code_index_push_nest(&result->nest_list, nest);
}
}

result->nest_array = code_index_nest_ptr_array_from_list(state->arena, &result->nest_list);

state->scope_counter -= 1;

return(result);
}

function Code_Index_Nest*
generic_parse_paren(Code_Index_File *index, Generic_Parse_State *state){
Token *token = token_it_read(&state->it);
Code_Index_Nest *result = push_array_zero(state->arena, Code_Index_Nest, 1);
result->kind = CodeIndexNest_Paren;
result->open = Ii64(token);
result->close = Ii64(max_i64);
result->file = index;

i64 manifested_characters_on_line = 0;
{
u8 *ptr = state->prev_line_start;
u8 *end_ptr = state->contents.str + token->pos;
// NOTE(allen): Initial whitespace
for (;ptr < end_ptr; ptr += 1){
if (!character_is_whitespace(*ptr)){
break;
}
}
// NOTE(allen): Manifested characters
manifested_characters_on_line = (i64)(end_ptr - ptr) + token->size;
}

state->paren_counter += 1;

generic_parse_inc(state);
for (;;){
generic_parse_skip_soft_tokens(index, state);
token = token_it_read(&state->it);
if (token == 0 || state->finished){
break;
}

if (state->in_preprocessor){
if (!HasFlag(token->flags, TokenBaseFlag_PreprocessorBody) ||
    token->kind == TokenBaseKind_Preprocessor){
break;
}
}
else{
if (token->kind == TokenBaseKind_Preprocessor){
Code_Index_Nest *nest = generic_parse_preprocessor(index, state);
code_index_push_nest(&index->nest_list, nest);
continue;
}
}

if (token->kind == TokenBaseKind_ParentheticalClose){
result->is_closed = true;
result->close = Ii64(token);
generic_parse_inc(state);
break;
}

if (token->kind == TokenBaseKind_ScopeClose){
break;
}

if (token->kind == TokenBaseKind_ScopeOpen){
Code_Index_Nest *nest = generic_parse_scope(index, state);
nest->parent = result;
code_index_push_nest(&result->nest_list, nest);
continue;
}

if (token->kind == TokenBaseKind_ParentheticalOpen){
Code_Index_Nest *nest = generic_parse_paren(index, state);
nest->parent = result;
code_index_push_nest(&result->nest_list, nest);
continue;
}

generic_parse_inc(state);
}

result->nest_array = code_index_nest_ptr_array_from_list(state->arena, &result->nest_list);

state->paren_counter -= 1;

return(result);
}

function b32
generic_parse_full_input_breaks(Code_Index_File *index, Generic_Parse_State *state, i32 limit){
b32 result = false;

i64 first_index = token_it_index(&state->it);
i64 one_past_last_index = first_index + limit;
for (;;){
generic_parse_skip_soft_tokens(index, state);
Token *token = token_it_read(&state->it);

if (token == 0 || state->finished){
result = true;
break;
}

if (token->kind == TokenBaseKind_Preprocessor){
Code_Index_Nest *nest = generic_parse_preprocessor(index, state);
code_index_push_nest(&index->nest_list, nest);
}
else if (token->kind == TokenBaseKind_ScopeOpen){
Code_Index_Nest *nest = generic_parse_scope(index, state);
code_index_push_nest(&index->nest_list, nest);
}
else if (token->kind == TokenBaseKind_ParentheticalOpen){
Code_Index_Nest *nest = generic_parse_paren(index, state);
code_index_push_nest(&index->nest_list, nest);
}
else if (state->do_cpp_parse){
if (token->sub_kind == TokenCppKind_Struct ||
    token->sub_kind == TokenCppKind_Union ||
    token->sub_kind == TokenCppKind_Enum){
cpp_parse_type_structure(index, state, 0);
}
else if (token->sub_kind == TokenCppKind_Typedef){
cpp_parse_type_def(index, state, 0);
}
else if (token->sub_kind == TokenCppKind_Identifier){
cpp_parse_function(index, state, 0);
}
else{
generic_parse_inc(state);
}
}
else{
generic_parse_inc(state);
}

i64 index = token_it_index(&state->it);
if (index >= one_past_last_index){
token = token_it_read(&state->it);
if (token == 0){
result = true;
}
break;
}
}

if (result){
index->nest_array = code_index_nest_ptr_array_from_list(state->arena, &index->nest_list);
index->note_array = code_index_note_ptr_array_from_list(state->arena, &index->note_list);
}

return(result);
}


////////////////////////////////
// NOTE(allen): Not sure

function void
default_comment_index(Application_Links *app, Arena *arena, Code_Index_File *index, Token *token, String_Const_u8 contents){

}

function void
generic_parse_init(Application_Links *app, Arena *arena, String_Const_u8 contents, Token_Array *tokens, Generic_Parse_State *state){
generic_parse_init(app, arena, contents, tokens, default_comment_index, state);
}


////////////////////////////////
// NOTE(allen): Virtual Whitespace Layout

function Token_Pair
layout_token_pair(Token_Array *tokens, i64 pos){
Token_Pair result = {};
Token_Iterator_Array it = token_iterator_pos(0, tokens, pos);
Token *b = token_it_read(&it);
if (b != 0){
if (b->kind == TokenBaseKind_Whitespace){
token_it_inc_non_whitespace(&it);
b = token_it_read(&it);
}
}
token_it_dec_non_whitespace(&it);
Token *a = token_it_read(&it);
if (a != 0){
result.a = *a;
}
if (b != 0){
result.b = *b;
}
return(result);
}

function f32
layout_index_x_shift(Application_Links *app, Layout_Reflex *reflex, Code_Index_Nest *nest, i64 pos, f32 regular_indent, b32 *unresolved_dependence){
f32 result = 0.f;
if (nest != 0){
switch (nest->kind){
case CodeIndexNest_Scope:
case CodeIndexNest_Preprocessor:
{
result = layout_index_x_shift(app, reflex, nest->parent, pos, regular_indent, unresolved_dependence);
if (nest->open.min < pos && nest->open.max <= pos &&
    (!nest->is_closed || pos < nest->close.min)){
result += regular_indent;
}
}break;

case CodeIndexNest_Statement:
{
result = layout_index_x_shift(app, reflex, nest->parent, pos, regular_indent, unresolved_dependence);
if (nest->open.min < pos && nest->open.max <= pos &&
    (!nest->is_closed || pos < nest->close.min)){
result += regular_indent;
}
}break;

case CodeIndexNest_Paren:
{
Rect_f32 box = layout_reflex_get_rect(app, reflex, nest->open.max - 1, unresolved_dependence);
result = box.x1;
}break;
}
}
return(result);
}

function f32
layout_index_x_shift(Application_Links *app, Layout_Reflex *reflex, Code_Index_Nest *nest, i64 pos, f32 regular_indent){
b32 ignore;
return(layout_index_x_shift(app, reflex, nest, pos, regular_indent, &ignore));
}

function f32
layout_index_x_shift(Application_Links *app, Layout_Reflex *reflex, Code_Index_File *file, i64 pos, f32 regular_indent, b32 *unresolved_dependence){
f32 indent = 0;
Code_Index_Nest *nest = code_index_get_nest(file, pos);
if (nest != 0){
indent = layout_index_x_shift(app, reflex, nest, pos, regular_indent, unresolved_dependence);
}
return(indent);
}

function f32
layout_index_x_shift(Application_Links *app, Layout_Reflex *reflex, Code_Index_File *file, i64 pos, f32 regular_indent){
b32 ignore;
return(layout_index_x_shift(app, reflex, file, pos, regular_indent, &ignore));
}

function void
layout_index__emit_chunk(LefRig_TopBot_Layout_Vars *pos_vars, Face_ID face, Arena *arena, u8 *text_str, i64 range_first, u8 *ptr, u8 *end, Layout_Item_List *list){
for (;ptr < end;){
Character_Consume_Result consume = utf8_consume(ptr, (u64)(end - ptr));
if (consume.codepoint != '\r'){
i64 index = layout_index_from_ptr(ptr, text_str, range_first);
if (consume.codepoint != max_u32){
lr_tb_write(pos_vars, face, arena, list, index, consume.codepoint);
}
else{
lr_tb_write_byte(pos_vars, face, arena, list, index, *ptr);
}
}
ptr += consume.inc;
}
}

function i32
layout_token_score_wrap_token(Token_Pair *pair, Token_Cpp_Kind kind){
i32 result = 0;
if (pair->a.sub_kind != kind && pair->b.sub_kind == kind){
result -= 1;
}
else if (pair->a.sub_kind == kind && pair->b.sub_kind != kind){
result += 1;
}
return(result);
}

function Layout_Item_List
layout_index__inner(Application_Links *app, Arena *arena, Buffer_ID buffer, Range_i64 range, Face_ID face, f32 width, Code_Index_File *file, Layout_Wrap_Kind kind){
Scratch_Block scratch(app, arena);

Token_Array tokens = get_token_array_from_buffer(app, buffer);
Token_Array *tokens_ptr = &tokens;

Layout_Item_List list = get_empty_item_list(range);
String_Const_u8 text = push_buffer_range(app, scratch, buffer, range);

Face_Advance_Map advance_map = get_face_advance_map(app, face);
Face_Metrics metrics = get_face_metrics(app, face);
f32 tab_width = (f32)def_get_config_u64(app, vars_save_string_lit("default_tab_width"));
tab_width = clamp_bot(1, tab_width);
LefRig_TopBot_Layout_Vars pos_vars = get_lr_tb_layout_vars(&advance_map, &metrics, tab_width, width);

u64 vw_indent = def_get_config_u64(app, vars_save_string_lit("virtual_whitespace_regular_indent"));
f32 regular_indent = metrics.space_advance*vw_indent;
f32 wrap_align_x = width - metrics.normal_advance;

Layout_Reflex reflex = get_layout_reflex(&list, buffer, width, face);

if (text.size == 0){
lr_tb_write_blank(&pos_vars, face, arena, &list, range.start);
}
else{
b32 first_of_the_line = true;
Newline_Layout_Vars newline_vars = get_newline_layout_vars();

u8 *ptr = text.str;
u8 *end_ptr = ptr + text.size;
u8 *word_ptr = ptr;

u8 *pending_wrap_ptr = ptr;
f32 pending_wrap_x = 0.f;
i32 pending_wrap_paren_nest_count = 0;
i32 pending_wrap_token_score = 0;
f32 pending_wrap_accumulated_w = 0.f;

start:
if (ptr == end_ptr){
i64 index = layout_index_from_ptr(ptr, text.str, range.first);
f32 shift = layout_index_x_shift(app, &reflex, file, index, regular_indent);
lr_tb_advance_x_without_item(&pos_vars, shift);
goto finish;
}

if (!character_is_whitespace(*ptr)){
i64 index = layout_index_from_ptr(ptr, text.str, range.first);
f32 shift = layout_index_x_shift(app, &reflex, file, index, regular_indent);
lr_tb_advance_x_without_item(&pos_vars, shift);
goto consuming_non_whitespace;
}

{
for (;ptr < end_ptr; ptr += 1){
if (!character_is_whitespace(*ptr)){
pending_wrap_ptr = ptr;
word_ptr = ptr;
i64 index = layout_index_from_ptr(ptr, text.str, range.first);
f32 shift = layout_index_x_shift(app, &reflex, file, index, regular_indent);
lr_tb_advance_x_without_item(&pos_vars, shift);
goto consuming_non_whitespace;
}
if (*ptr == '\r'){
i64 index = layout_index_from_ptr(ptr, text.str, range.first);
newline_layout_consume_CR(&newline_vars, index);
}
else if (*ptr == '\n'){
pending_wrap_ptr = ptr;
i64 index = layout_index_from_ptr(ptr, text.str, range.first);
f32 shift = layout_index_x_shift(app, &reflex, file, index, regular_indent);
lr_tb_advance_x_without_item(&pos_vars, shift);
goto consuming_normal_whitespace;
}
}

if (ptr == end_ptr){
pending_wrap_ptr = ptr;
i64 index = layout_index_from_ptr(ptr - 1, text.str, range.first);
f32 shift = layout_index_x_shift(app, &reflex, file, index, regular_indent);
lr_tb_advance_x_without_item(&pos_vars, shift);
goto finish;
}
}

consuming_non_whitespace:
{
for (;ptr <= end_ptr; ptr += 1){
if (ptr == end_ptr || character_is_whitespace(*ptr)){
break;
}
}

// NOTE(allen): measure this word
newline_layout_consume_default(&newline_vars);
String_Const_u8 word = SCu8(word_ptr, ptr);
u8 *word_end = ptr;
{
f32 word_advance = 0.f;
ptr = word.str;
for (;ptr < word_end;){
Character_Consume_Result consume = utf8_consume(ptr, (u64)(word_end - ptr));
if (consume.codepoint != max_u32){
word_advance += lr_tb_advance(&pos_vars, face, consume.codepoint);
}
else{
word_advance += lr_tb_advance_byte(&pos_vars);
}
ptr += consume.inc;
}
pending_wrap_accumulated_w += word_advance;
}

if (!first_of_the_line && (kind == Layout_Wrapped) && lr_tb_crosses_width(&pos_vars, pending_wrap_accumulated_w)){
i64 index = layout_index_from_ptr(pending_wrap_ptr, text.str, range.first);
lr_tb_align_rightward(&pos_vars, wrap_align_x);
lr_tb_write_ghost(&pos_vars, face, arena, &list, index, '\\');

lr_tb_next_line(&pos_vars);
#if 0
f32 shift = layout_index_x_shift(app, &reflex, file, index, regular_indent);
lr_tb_advance_x_without_item(&pos_vars, shift);
#endif

ptr = pending_wrap_ptr;
pending_wrap_accumulated_w = 0.f;
first_of_the_line = true;
goto start;
}
}

consuming_normal_whitespace:
for (; ptr < end_ptr; ptr += 1){
if (!character_is_whitespace(*ptr)){
u8 *new_wrap_ptr = ptr;

i64 index = layout_index_from_ptr(new_wrap_ptr, text.str, range.first);
Code_Index_Nest *new_wrap_nest = code_index_get_nest(file, index);
b32 invalid_wrap_x = false;
f32 new_wrap_x = layout_index_x_shift(app, &reflex, new_wrap_nest, index, regular_indent, &invalid_wrap_x);
if (invalid_wrap_x){
new_wrap_x = max_f32;
}

i32 new_wrap_paren_nest_count = 0;
for (Code_Index_Nest *nest = new_wrap_nest;
     nest != 0;
     nest = nest->parent){
if (nest->kind == CodeIndexNest_Paren){
new_wrap_paren_nest_count += 1;
}
}

Token_Pair new_wrap_token_pair = layout_token_pair(tokens_ptr, index);

// TODO(allen): pull out the token scoring part and make it replacable for other
// language's token based wrap scoring needs.
i32 token_score = 0;
if (new_wrap_token_pair.a.kind == TokenBaseKind_Keyword){
if (new_wrap_token_pair.b.kind == TokenBaseKind_ParentheticalOpen ||
    new_wrap_token_pair.b.kind == TokenBaseKind_Keyword){
token_score -= 2;
}
}
token_score += layout_token_score_wrap_token(&new_wrap_token_pair, TokenCppKind_Eq);
token_score += layout_token_score_wrap_token(&new_wrap_token_pair, TokenCppKind_PlusEq);
token_score += layout_token_score_wrap_token(&new_wrap_token_pair, TokenCppKind_MinusEq);
token_score += layout_token_score_wrap_token(&new_wrap_token_pair, TokenCppKind_StarEq);
token_score += layout_token_score_wrap_token(&new_wrap_token_pair, TokenCppKind_DivEq);
token_score += layout_token_score_wrap_token(&new_wrap_token_pair, TokenCppKind_ModEq);
token_score += layout_token_score_wrap_token(&new_wrap_token_pair, TokenCppKind_LeftLeftEq);
token_score += layout_token_score_wrap_token(&new_wrap_token_pair, TokenCppKind_RightRightEq);
token_score += layout_token_score_wrap_token(&new_wrap_token_pair, TokenCppKind_Comma);
token_score += layout_token_score_wrap_token(&new_wrap_token_pair, TokenCppKind_AndAnd);
token_score += layout_token_score_wrap_token(&new_wrap_token_pair, TokenCppKind_OrOr);
token_score += layout_token_score_wrap_token(&new_wrap_token_pair, TokenCppKind_Ternary);
token_score += layout_token_score_wrap_token(&new_wrap_token_pair, TokenCppKind_Colon);
token_score += layout_token_score_wrap_token(&new_wrap_token_pair, TokenCppKind_Semicolon);

i32 new_wrap_token_score = token_score;

b32 new_wrap_ptr_is_better = false;
if (first_of_the_line){
new_wrap_ptr_is_better = true;
}
else{
if (new_wrap_token_score > pending_wrap_token_score){
new_wrap_ptr_is_better = true;
}
else if (new_wrap_token_score == pending_wrap_token_score){
f32 new_score = new_wrap_paren_nest_count*10.f + new_wrap_x;
f32 old_score = pending_wrap_paren_nest_count*10.f + pending_wrap_x + metrics.normal_advance*4.f + pending_wrap_accumulated_w*0.5f;

if (new_score < old_score){
new_wrap_ptr_is_better = true;
}
}
}

if (new_wrap_ptr_is_better){
layout_index__emit_chunk(&pos_vars, face, arena, text.str, range.first, pending_wrap_ptr, new_wrap_ptr, &list);
first_of_the_line = false;

pending_wrap_ptr = new_wrap_ptr;
pending_wrap_paren_nest_count = new_wrap_paren_nest_count;
pending_wrap_x = layout_index_x_shift(app, &reflex, new_wrap_nest, index, regular_indent);
pending_wrap_paren_nest_count = new_wrap_paren_nest_count;
pending_wrap_token_score = new_wrap_token_score;
pending_wrap_accumulated_w = 0.f;
}

word_ptr = ptr;
goto consuming_non_whitespace;
}

i64 index = layout_index_from_ptr(ptr, text.str, range.first);
switch (*ptr){
default:
{
newline_layout_consume_default(&newline_vars);
pending_wrap_accumulated_w += lr_tb_advance(&pos_vars, face, *ptr);
}break;

case '\r':
{
newline_layout_consume_CR(&newline_vars, index);
}break;

case '\n':
{
layout_index__emit_chunk(&pos_vars, face, arena, text.str, range.first, pending_wrap_ptr, ptr, &list);
pending_wrap_ptr = ptr + 1;
pending_wrap_accumulated_w = 0.f;

u64 newline_index = newline_layout_consume_LF(&newline_vars, index);
lr_tb_write_blank(&pos_vars, face, arena, &list, newline_index);
lr_tb_next_line(&pos_vars);
first_of_the_line = true;
ptr += 1;
goto start;
}break;
}
}

finish:
if (newline_layout_consume_finish(&newline_vars)){
layout_index__emit_chunk(&pos_vars, face, arena, text.str, range.first, pending_wrap_ptr, ptr, &list);
i64 index = layout_index_from_ptr(ptr, text.str, range.first);
lr_tb_write_blank(&pos_vars, face, arena, &list, index);
}
}

layout_item_list_finish(&list, -pos_vars.line_to_text_shift);

return(list);
}

function Layout_Item_List
layout_virt_indent_index(Application_Links *app, Arena *arena, Buffer_ID buffer, Range_i64 range, Face_ID face, f32 width, Layout_Wrap_Kind kind){
Layout_Item_List result = {};

b32 enable_virtual_whitespace = def_get_config_b32(vars_save_string_lit("enable_virtual_whitespace"));
if (enable_virtual_whitespace){
code_index_lock();
Code_Index_File *file = code_index_get_file(buffer);
if (file != 0){
result = layout_index__inner(app, arena, buffer, range, face, width, file, kind);
}
code_index_unlock();
if (file == 0){
result = layout_virt_indent_literal(app, arena, buffer, range, face, width, kind);
}
}
else{
result = layout_basic(app, arena, buffer, range, face, width, kind);
}

return(result);
}

function Layout_Item_List
layout_virt_indent_index_unwrapped(Application_Links *app, Arena *arena, Buffer_ID buffer, Range_i64 range, Face_ID face, f32 width){
return(layout_virt_indent_index(app, arena, buffer, range, face, width, Layout_Unwrapped));
}

function Layout_Item_List
layout_virt_indent_index_wrapped(Application_Links *app, Arena *arena, Buffer_ID buffer, Range_i64 range, Face_ID face, f32 width){
return(layout_virt_indent_index(app, arena, buffer, range, face, width, Layout_Wrapped));
}

function Layout_Item_List
layout_virt_indent_index_generic(Application_Links *app, Arena *arena, Buffer_ID buffer, Range_i64 range, Face_ID face, f32 width){
Managed_Scope scope = buffer_get_managed_scope(app, buffer);
b32 *wrap_lines_ptr = scope_attachment(app, scope, buffer_wrap_lines, b32);
b32 wrap_lines = (wrap_lines_ptr != 0 && *wrap_lines_ptr);
return(layout_virt_indent_index(app, arena, buffer, range, face, width, wrap_lines?Layout_Wrapped:Layout_Unwrapped));
}

CUSTOM_COMMAND_SIG(toggle_virtual_whitespace)
CUSTOM_DOC("Toggles virtual whitespace for all files.")
{
String_ID key = vars_save_string_lit("enable_virtual_whitespace");
b32 enable_virtual_whitespace = def_get_config_b32(key);
def_set_config_b32(key, !enable_virtual_whitespace);
}

// BOTTOM